BY-COVID - WP5 - Baseline Use Case: COVID-19 vaccine effectiveness assessment

Matching cases to controls (1:1) and assessing covariate balance after matching

Covariate balance is the extent to which the distribution of covariates is similar across the intervention groups.

Standardized mean differences

The Standardized Mean Difference (SMD) represents a standardized difference in mean between contrasted intervention groups for each covariate.

Means intervention group Means control group Standardized mean difference
distance 0.89839344 0.89700714 0.125175777
age_cd 11.59381714 11.58271865 0.003749979
sex_cd 1.46657914 1.48366702 -0.031811299
residence_area_cd731 0.13965147 0.14646997 -0.019671111
residence_area_cd732 0.14108379 0.12961012 0.032960105
residence_area_cd733 0.71926474 0.72391992 -0.010359603
institutionalized_blTRUE 0.02781093 0.02950474 -0.010301042
foreign_blTRUE 0.15170685 0.12961012 0.061596004
pregnancy_blTRUE 0.01181666 0.02107482 -0.085675800
essential_worker_blTRUE 0.02757221 0.02845100 -0.005366853
comorbidities_blTRUE 0.45977560 0.47523709 -0.031023533
immunestatus_blTRUE 0.28037718 0.26343519 0.037717288
Means intervention group Means control group Standardized mean difference
distance 0.50016888 0.49983112 0.036925901
age_cd 11.68012685 11.66701903 0.004448472
sex_cd 1.47420719 1.47843552 -0.007892363
residence_area_cd731 0.13594080 0.14164905 -0.016655434
residence_area_cd732 0.14630021 0.13615222 0.028714750
residence_area_cd733 0.71775899 0.72219873 -0.009864130
institutionalized_blTRUE 0.02706131 0.02684989 0.001302932
foreign_blTRUE 0.15031712 0.15031712 0.000000000
pregnancy_blTRUE 0.01162791 0.01310782 -0.013804665
essential_worker_blTRUE 0.02684989 0.02896406 -0.013079094
comorbidities_blTRUE 0.45539112 0.45687104 -0.002971682
immunestatus_blTRUE 0.27526427 0.27547569 -0.000473341

Variance ratios

The variance ratio (VR) represents the ratio of the variance in the contracted intervention groups for each covariate. A VR close to 1, implies that variances are similar in the compared groups and as such indicates good covariate balance.

Var. Ratio
distance 0.7576281
age_cd 0.9708949
sex_cd 0.9875230
residence_area_cd731 NA
residence_area_cd732 NA
residence_area_cd733 NA
institutionalized_blTRUE NA
foreign_blTRUE NA
pregnancy_blTRUE NA
essential_worker_blTRUE NA
comorbidities_blTRUE NA
immunestatus_blTRUE NA
Var. Ratio
distance 0.9813426
age_cd 0.9948747
sex_cd 1.0082098
residence_area_cd731 NA
residence_area_cd732 NA
residence_area_cd733 NA
institutionalized_blTRUE NA
foreign_blTRUE NA
pregnancy_blTRUE NA
essential_worker_blTRUE NA
comorbidities_blTRUE NA
immunestatus_blTRUE NA

Propensity score distribution